1. Field of the Invention
This invention relates generally to the field of inflatable penile erection devices, and more specifically relates to an improved stiffener cylinder which is implanted into the corpus cavernosum of the penis.
2. Description of the Prior Art
There is an increasing amount of activity in the field of penile erection devices to aid the male suffering the affliction of erectile impotence. See, for example, copending U.S. patent application Ser. No. 476,931, now U.S. Pat. No. 4,559,931 entitled "Manually Actuated Fully Implantable Penile Erection Device." In this and other devices, fluid-actuated stiffener cylinders are implanted in each of the corpora cavernosa, and serve to effect the erect state when filled with fluid and to effect the flaccid state when relieved of fluid.
Present stiffener cylinders for inflatable penile erection devices have several serious deficiencies. One such deficiency is that they do not extend in length to any significant degree in the erect state. For example, these devices extend only by approximately 0.5% in going from the flaccid to the erect state, an almost imperceptible length change. A second deficiency is that in the flaccid state, the cylinders buckle where the pendulous portion enters the body. This could lead to cracking and leakage of fluid through the cylinders after several years of flexing.
A third deficiency is related to the implantation of two cylinders in the corpora cavernosa of the penis. The cylinders are circular in cross section and retain their circular shape when they expand. Because these cylinders are mounted side by side in the penis, when they are inflated, the pendulous portion of the penis assumes a flattened shape which is not physiologically equivalent to the generally circular cross section of the normally erect penis.
The U.S. Pat. No. 4,267,829 to Burton et al (FIG. 4) discloses a corrugated cloth material sandwiched between two elastomer cylinders as a structure for a penile cylinder. Although the corrugated cloth does allow some longitudinal expansion, while intentionally disallowing radial expansion, because the corrugations of the cloth are confined between two elastomer cylinders, longitudinal expansion is extremely restricted and the buckling phenomenon at the base of the pendulous portion of the penile cylinder is still present. Thus, the Burton et al patent does not disclose a device or method for obtaining a significantly longer length of the penis during erection, does not solve the problem of excessive stress at the point where the cylinder buckles in its flaccid state, and still produces a flattened shape when two cylinders in side-by-side relationship are inflated to an erect state.